Someone who attempts to include themselves in a conversation or groupgathering with the disapproval of the other group members.
A scrape can be notified of their scraping through the use of the words "scrape out"

When someone rats in on something they aren't involved in or asked about.

For example,
Angus: what did you get in the test Sean?
Charlie: oh yeah I found that really hard I only got 60%
Angus: Charlie I asked Sean not you you're such 'a scrape'
Sean: scrape out Charlie he asked me not you